Disk drives are a type of information storage device that store information on at least one spinning disk. Other types of information storage devices include, for example, magnetic tape drives which retrieve stored information on magnetic tape (e.g. linear tape drive, helical scan tape drive). There are several types of disk drives. Magnetic hard disk drives typically store information on non-removable rigid magnetic disks. There are also optical disk drives, which typically retrieve information stored on removable optical disk media. Also for example, there are magneto-optical disk drives, which share some of the characteristics of optical disk drives and magnetic hard disk drives.
All types of disk drives typically include a spindle motor that supports and spins at least one disk media. The spindle motor typically includes a lubricant (e.g. grease in a ball bearing spindle, fluid of a fluid bearing spindle, etc.) that is desired to be sealed within the spindle so as to not excessively outgas, migrate, or otherwise contaminate the inside environment of the disk drive. Such lubricant outgassing or migration can contaminate the recording head/disk interface and thereby adversely affect the performance and/or reliability of the disk drive. Therefore, disk drive spindles may include a seal to reduce lubricant outgassing or migration into the disk drive internal environment.
Pumping seals have been disclosed in the past to reduce lubricant outgassing or migration into the disk drive internal environment. Such seals may have pumping air grooves on one of a pair of adjacent surfaces that exhibit relative motion due to spindle rotation. Such pumping grooves can pump air towards a region of locally increased air pressure that the grooves create between the spindle and the rest of the disk drive internal environment. Such region of locally increased pressure can reduce the outgassing, migration, or diffusion of lubricant from the spindle into the rest of the internal environment of the disk drive.
However, a grooved pumping seal requires the corresponding pair of adjacent surfaces in relative motion (due to spindle rotation) to be very closely spaced (e.g. about 25 microns or less), or else the local increase in air pressure due to the pumping grooves may be negligible. Such close spacing of adjacent surfaces in relative motion requires tight tolerances, precision fabrication, and careful handling during assembly, which can undesirably raise the cost of spindle and disk drive manufacture. Therefore, there is a need in the art for a disk drive spindle that includes an active labyrinth seal that adequately reduces lubricant migration or outgassing, but also allows a greater or relaxed spacing between adjacent surfaces in relative motion, for reduced manufacturing cost.